A heat dissipating apparatus includes a heat sink, a fan, and an airflow guide. The heat sink includes a conducting base board and a number of parallel fins vertically extending from the conducting base board. An air intake and an air outlet are defined in opposite ends of the heat sink. The airflow guide includes a mounting cover accommodating the heat sink, and a guiding element connected to the mounting cover. The fan is mounted to the mounting cover and at the air intake of the heat sink. The guiding element is arranged at the air outlet of the heat sink. The guiding element includes a guiding board. An angle between the guiding board and the fins at the air outlet is less than 90 degrees and more than 0 degrees.